PROJECT SUMMARY This project will provide laboratory support for a large, cross-sectional COVID-19 seroprevalence study that will be conducted in 23-25 communities in the United States: the SARS-CoV-2 Seroprevalence Study (COVID-19 Prevention Trials Network [CoVPN] 5002). The CoVPN 5002 study will include collection of data and specimens from up to 98,000 persons, including persons living in nursing homes and assisted living facilities, persons attending clinics, and persons living in study communities. The study will include children (ages 2 months and older) and adults. Participants will be tested for COVID-19 in real time using SARS-CoV-2 RNA assays. Seroprevalence will be assessed retrospectively using stored specimens from all participants using a sensitive and specific SARS-CoV-2 IgG assay (Abbott ARCHITECT COVID-19 IgG test). A subset of specimens from CoVPN 5002 will also be used to evaluate the performance of diagnostic and serologic SARS-CoV-2 assays using alternate specimen types (saliva and dried blood spots). Collection of these sample types is simpler and less invasive than collection of nasal swabs or collection of blood samples by phlebotomy. This project will also use of specialized assays to evaluate the serologic response to SARS-CoV-2. This will include use of a massively multiplexed antibody profiling assay (CoronaScan) to measure antibody binding to SARS-CoV-2 peptides spanning the viral genome. This analysis will provide information on the fine specificity of the antibody response to SARS-CoV-2 and reactivity to other coronaviruses and other viruses that cause respiratory illnesses. This testing may also identify participants who have false positive or false negative test results using the ARCHITECT COVID-19 IgG test. Specimens that have antibodies to the SARS-CoV-2 spike protein (identified using the CoronaScan assay) will be further assessed using a phenotypic recombinant viral neutralization assay (PhenoSense Anti-SARS-CoV-2 Neutralizing Antibody Assay). This analysis may identify viral epitopes associated with viral neutralization and may also identify demographic and clinical factors associated with the presence of neutralizing antibodies. Specimens from CoVPN 5002 will also be used for further development and evaluation of a novel, massively multiplexed pathogen detection assay, cRASL-Seq, that does not require RNA extraction. Findings from this research will inform the design of clinical trials for SARS-CoV-2 prevention and treatment by providing information about the seroprevalence of COVID-19 in diverse geographic regions and participants groups, including asymptomatic and symptomatic individuals, children and adults in the general population, and adults at increased risk for COVID-19.